1 Pediatric Emergency and Critical Care Division, Hospital Clínico Universitario de Santiago, SERGAS, Santiago de Compostela, Spain, Universidade de Santiago de Compostela, CLINURSID Investigation Group, Santiago de Compostela, Spain, Mother-Child Health and Development Network (Red SAMID) of Carlos III Health Institute, RETICS funded by the PN I+D+I 2008-2011, Madrid, Spain, ISCIII-Sub-Directorate General for Research Assessment and Promotion and the European Regional Development Fund (ERDF) ref RD12/0026, Madrid, Spain, Iberoamerican Network for Study of Cardiorespiratory Arrest in Childhood (CYTED), Madrid, Spain; Pediatric Intensive Care Unit, Hospital General Universitario Gregorio Marañón, Universidad Complutense, Madrid, Spain, Mother-Child Health and Development Network (Red SAMID) of Carlos III Health Institute, RETICS funded by the PN I+D+I 2008-2011, Madrid, Spain, ISCIII-Sub-Directorate General for Research Assessment and Promotion and the European Regional Development Fund (ERDF) ref RD12/0026, Madrid, Spain, Iberoamerican Network for Study of Cardiorespiratory Arrest in Childhood (CYTED), Madrid, Spain.